Apparatus for testing liquid crystal display panel

ABSTRACT

An apparatus for testing a liquid crystal display (LCD) panel which is capable of easily attaching or detaching a large polarizer to/from a test board when testing a large LCD panel, the apparatus comprising a test board for outputting light to an LCD panel which is placed thereon, a polarizer fixing unit rotatably formed at the test board and having a groove in which a polarizer is inserted, and a stop formed at the test board to fix the polarizer fixing unit to a desired position.

This application claims the benefit of Korean Patent Application No.10-2005-134590, filed on Dec. 29, 2005, which is hereby incorporated byreference for all purposes as if fully set forth herein. Thisapplication incorporates by reference co-pending application Ser. No.10/184,096, filed on Jun. 28, 2002 entitled “SYSTEM AND METHOD FORMANUFACTURING LIQUID CRYSTAL DISPLAY DEVICES FROM LARGE MOTHER SUBSTRATEPANELS” (Attorney Docket Number 8733.666.00); and co-pendingapplication, Ser. No. ______, filed on Jun. 29, 2006, entitled “METHODSOF MANUFACTURING LIQUID CRYSTAL DISPLAY DEVICES” (Attorney Docket Number8733.1713.00) for all purposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus for testing a liquidcrystal display panel, and particularly, to an apparatus for testing aliquid crystal display panel which is capable of easily fixing apolarizer having a large size by inserting the polarizer into arotatable polarizer fixing unit.

2. Discussion of the Related Art

With the continuing deployment of various portable electric devices suchas mobile phones, personal digital assistants (PDA), notebook computers,various types of flat panel display devices such as liquid crystaldisplays (LCDs), plasma display panels (PDPs), field emission displays(FEDs), and vacuum florescent displays (VFDs), having a compactconstruction, light weight, and low power-consumption characteristicsare being developed. LCDs are extensively used because they are drivablewith relatively simple circuitry and because of their superior abilityto display images.

The liquid crystal display (LCD) device takes advantage of therefractive index anisotropy of liquid crystal to display information ona screen. As shown in FIG. 1, a typical LCD device 1 includes a lowersubstrate 5, an upper substrate 3, and a liquid crystal layer 7 disposedbetween the lower substrate 5 and the upper substrate 3. The lowersubstrate 5 is a switching device array substrate. Although not shown,the lower substrate 5 is provided with a plurality of pixels, each ofwhich is provided with a switching device such as a Thin Film Transistor(TFT). The upper substrate 3 is a color filter substrate and includes acolor filter layer for implementing a substantial color. In addition,the lower substrate 5 and the upper substrate 3 are respectivelyprovided with a pixel electrode and a common electrode and are eachcoated with an alignment layer for aligning liquid crystal molecules ofthe liquid crystal layer 7.

The lower and upper substrates 5 and 3 are bonded to each other by asealant 9. The liquid crystal layer 7 is formed between the lower andupper substrates 5 and 3. A driving device applies potentials to thepixel and common electrodes to control using the switching device formedat the lower substrate 5 to control the orientation of the liquidcrystal molecules and accordingly to control an amount of lighttransmitted through the liquid crystal layer 7 to display images.

A fabrication process of the LCD device includes a switching devicearray substrate forming process for forming the switching devices at thelower substrate 5, a color filter forming process for forming the colorfilter at the upper substrate 3, and a cell forming process. Thefabricating process of the LCD device will now be explained withreference to FIG. 2.

First, as part of the switching device array forming process, aplurality of gate lines and a plurality of data lines are arranged onthe lower substrate 5 to define pixel regions. A TFT to be used as aswitching device is connected to each gate line and each data line andis formed in each pixel region (S101). The switching device arrayforming process further includes forming a pixel electrode connected tothe TFT to drive the liquid crystal layer 7 when a signal is applied viathe TFT.

The color filter forming process include forming a color filter layerfor implementing R, G and B colors on the upper substrate 3, and aforming common electrode thereon (S104).

An alignment layer is coated on each of the upper and lower substrate 3and 5. The alignment layers are rubbed to provide an alignmentcontrolling force or a surface fixing force to set the initial alignment(i.e., a pretilt angle and an alignment direction) of the liquid crystalmolecules of the liquid crystal layer 7 disposed between the upper andlower substrates 3 and 5 (S102 and S105). Spacers are dispersed over thelower substrate 5 for maintaining a cell gap between the upper and lowersubstrates 3 and 5 and a sealant 9 is disposed on an outer periphery ofthe upper substrate 3 for bonding together the lower substrate 5 and theupper substrate by applying a pressure thereto (S103, S106 and S107).

The lower and upper substrates 5 and 3 are formed from large sized glasssubstrates. In other words, a plurality of panel regions are formed onthe large glass substrates and the TFT (i.e., the switching device) andthe color filter layer are formed on each panel region. Accordingly, theglass substrate must be cut and processed in order to fabricate unit LCDpanels (S108). A liquid crystal may be injected into the processed unitLCD panels through a liquid crystal injection opening and then theinjection opening is encapsulated to form the liquid crystal layer 7.Each unit LCD panel is inspected to complete the fabrication process ofthe LCD panel (S109 and S110).

The LCD panel is typically tested (inspected) by a visual inspection andan electrical lighting test. The lighting test is performed by applyinga signal to a completely fabricated LCD panel to detect (test) whethervarious electric devices are operating normally, while the visualinspection is performed by an operator conducting a naked eye inspectionof the LCD panel to determine whether the LCD panel has been defectivelyfabricated.

A typical apparatus for visually inspecting an LCD panel includes a testboard having a lamp therein for outputting light. An LCD panel istransferred to the visual inspection apparatus to be placed on the testboard and a polarizer is positioned on the LCD panel. A signal isapplied to the LCD panel and the LCD panel is illuminated by lighttransmitted from the lamp provided in the test board. The operatorobserves light transmitted through the LCD panel to detect defects inthe LCD panel.

FIGS. 3A and 3B show a related art visual inspection apparatus fortesting an LCD panel appearance, wherein FIG. 3A is a side sectionalview of the visual inspection apparatus and FIG. 3B is a plane viewthereof.

As shown in FIGS. 3A and 3B, a related art apparatus for visuallyinspecting an LCD panel 20 includes a test board 22 including a lampinstalled therein for transmitting light to the LCD panel 1 placedthereon; a camera 24 positioned at an upper portion of the test board 22for capturing alignment marks (not shown) formed at an outer peripheryof the LCD panel 1 to thus determine whether the LCD panel 1 has beenaligned on the test board 22; a jig 32 disposed at a lower portion ofthe test board 22 supporting a polarizer 30 and having holes 27; and aplurality of jig pins 26 formed at the test board 22 to be inserted intothe holes 27 of the jig 32 to thus fix the jig 32 to the test board 22,thereby fixing the polarizer 30 onto the LCD panel 1.

The test board 22 is inclined by about 60° relative to the ground andhas a lamp therein. When an operator puts the LCD panel 1 on the testboard 22, the camera 24 captures the alignment marks formed on the LCDpanel 1 to provide information regarding the state of alignment of theLCD panel 1. With the LCD panel 1 aligned on the test board 22, theoperator inserts the jig pins 26 formed at the test board 22 into theholes 27 formed in the jig 32 to position the polarizer 30 on the LCDpanel 1. With the polarizer fixed, a signal is applied to the LCD panel1 and a transmissivity of light transmitted through the LCD panel ischanged according to a signal applied to the LCD panel 1. The operatorobserves the light transmitted through the polarizer 30 to evaluate thequality of the LCD panel.

The jig 32 supports the polarizer 30. The operator manipulates the jig32 rather than the polarizer 30 to position the polarizer 30 on the testboard 22. The jig pins 26 are inserted into the holes 27 formed in thejig 32 to fix the jig 32, and thus the polarizer 30, onto the test board22.

However, the above described visual inspection apparatus for the LCDpanel may generate problems as follows.

In order to fix the polarizer 30 by inserting the jig 32 into the jigpins 26, the operator must manually hold the jig 32 while inserting thejig pins 26 of the test board 22 into the holes 27 of the jig 32.However, with a the large-sized LCD panel 1, the corresponding largesize of the polarizer 30 makes it physically difficult or impossible forthe operator to manually insert the jig pins 26 into the holes 27 of thejig 32. In addition, while attaching or detaching the polarizer 30, thepolarizer 30 may strike the camera 24, resulting in damage to the camera24 or to the polarizer 30.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to an apparatus fortesting liquid crystal display panel that substantially obviates one ormore of the problems due to limitations and disadvantages of the relatedart.

An advantage of the present invention is to provide an apparatus fortesting a liquid crystal display panel that is capable of easilyattaching and detaching a polarizer by inserting a polarizer jig into agroove formed in a polarizer fixing unit to fix the polarizer.

Another advantage of the present invention is to provide an apparatusfor testing a liquid crystal display panel in which a polarizer fixingunit is rotatably constructed to be then perpendicularly inserted into apolarizer, and then the polarizer fixing unit is rotated to position thepolarizer on an LCD panel, thereby preventing the polarizer fromcolliding with other components.

Additional features and advantages of the invention will be set forth inthe description which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention. Theobjectives and other advantages of the invention will be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described, anapparatus for testing a liquid crystal display (LCD) panel includes: atest board to transmit light to an LCD panel which is placed thereon; apolarizer fixing unit rotatably formed at the test board and having agroove into which a polarizer is insertable; and a stop formed at thetest board to fix the polarizer fixing unit at a predetermined position.

In another aspect of the present invention, an apparatus for testing aliquid crystal display (LCD) panel includes: a test board to transmitlight to an LCD panel which is placed thereon; a jig to support apolarizer; and a polarizer fixing unit formed at the test board andhaving a groove into which the jig is insertable to thus fix thepolarizer.

In another aspect of the present invention, a method of fabricating aliquid crystal display (LCD) panel, the method includes: preparing afirst and a second substrate; performing a switching device arrayprocess on the first substrate; performing a color filter substrateprocess on the second substrate; bonding the first and second substratetogether; forming a liquid crystal layer between the substrates; cuttingthe attached substrates into a plurality of unit LCD panels; performinga visual inspection of a unit LCD panel of the plurality of unit LCDpanels using a visual inspection apparatus including: a test board totransmit light to a unit LCD panel disposed thereon; a polarizer fixingunit rotatably formed at the test board and having a groove into which apolarizer is insertable; and a stop formed at the test board to fix thepolarizer fixing unit at a predetermined position.

The foregoing and other objects, features, aspects and advantages of thepresent invention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

In the drawings:

FIG. 1 is a sectional view showing a typical LCD device;

FIG. 2 is a flowchart showing a related art method for fabricating anLCD device;

FIGS. 3A and 3B are views showing a related art apparatus for testing anappearance of an LCD panel;

FIGS. 4A and 4B are views showing an apparatus for testing an appearanceof an LCD panel according to an embodiment of the present invention; and

FIGS. 5A and 5B are views showing an operation of the apparatus fortesting an appearance of an LCD panel according to an embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Reference will now be made in detail to embodiments of the presentinvention, examples of which are illustrated in the accompanyingdrawings.

Hereinafter, an apparatus for testing an appearance of an LCD panelaccording to the present invention will now be explained in detail withreference to the attached drawings.

FIGS. 4A and 4B are views showing an apparatus for testing an appearanceof an LCD panel according to the present invention. As shown in FIGS. 4Aand 4B, an apparatus 120 for visual inspection of an LCD panel accordingto an embodiment of the present invention includes a test board 122 fortransmitting light to an LCD panel 101 placed thereon by use of a lampinstalled therein; a jig 132 for supporting a polarizer 130; and apolarizer fixing unit 126 formed at the test board 122 and in which thejig 132 is inserted.

The polarizer fixing unit 126 is provided such that the jig 132 forsupporting the polarizer 130 is inserted thereinto. An inserting groovefor the polarizer 130 is formed in the polarizer fixing unit 126 andaccordingly the jig 132 of the polarizer 130 is inserted into theinserting groove to fix the polarizer 130. The polarizer fixing unit 126is rotatable about a rotary shaft 127 to form a certain angle from thetest board 122. For example, the polarizer fixing unit 126 may berotatable to be perpendicular to the ground. The polarizer 130 caneasily be inserted into the inserting groove of the polarizer fixingunit 126 when the polarizing fixing unit is rotated downwardly to acertain angle such as in a perpendicular direction to the ground.

Furthermore, the test board 122 is provided with a stop 128 for settingthe rotation angle of the polarizer fixing unit 126. The polarizerfixing unit 126 may be rotated to a position where the polarizer 130 caneasily be inserted therein. Over-rotation of the polarizer fixing unit126 makes it more difficult to insert the polarizer 130 therein.Accordingly, the stop 128 is provided to stop the rotation of thepolarizer fixing unit 126 at a position where the polarizer 130 may beeasily inserted therein.

The stop 128 may include a fixing member 129 such as a magnet. Thefixing member 129 maintains the polarizing fixing unit 126 positioned atthe insertion position of the polarizer 130, and accordingly holds thepolarizer fixing unit 126 while the polarizer 130 is inserted into thepolarizer fixing unit 126. A unit for coupling to the fixing member 129may be provided to fix the polarizing fixing unit 126 to the fixingmember 129. For example, when the fixing member 129 is the magnet, aferrous metal plate may be provided on the polarizer fixing unit 126 tofix the polarizer fixing unit 126 at the desired position by a magneticforce of the magnet. Alternatively, when the fixing member 129 is abolt, the polarizer fixing unit 126 may have a nut threadable onto thebolt to fix the polarizer fixing unit at the desired position. Thefixing member 129 may be disposed in the polarizer fixing unit 126 andthe unit for coupling to the fixing member 129 may be disposed in thestop 128.

A method for testing an LCD panel using the apparatus for visuallyinspecting the LCD panel having such construction will now be explainedwith reference to FIGS. 5A and 5B.

First, a switching device array forming process is performed to formgate lines and data lines, thin film transistors, and a pixel electrodeon a first substrate and a color filter forming process is performed toform a color filter layer and a common electrode on a second substrate.A cell forming process is performed to bond the first and secondsubstrates. Various methods such as a vacuum injection method or aliquid crystal dispensing method are adapted to form a liquid crystallayer between the first and second substrates. The LCD panel 101 thathas undergone the switching device array forming process, the colorfilter forming process and the cell forming process is transferred to avisual inspection appearance testing process by a transferring apparatussuch as a conveyer. The transferred LCD panel 101 is placed on the testboard 122. As shown in FIG. 5A, the polarizer fixing unit 126 is rotatedto allow a groove 126 a formed in the polarizer fixing unit 126 to bepositioned upwardly. At this time, the polarizer fixing unit 126 isfixed to the stop 128 by the fixing member 129, to thus maintain thegroove 126 a positioned upwardly by being at an angle to the ground suchas perpendicular to the ground.

An operator then inserts the polarizer 130 that is supported by the jig132 downwardly into the groove 126 a of the polarizer fixing unit 126 tofix the polarizer 130. Then, as shown in FIG. 5B, the polarizer fixingunit 126 is rotated to position the polarizer 130 on the LCD panel 101.

With the polarizer 130 is positioned on the LCD panel 101, the camera124 is used to confirm the aligned state of the LCD panel 101. A signalis applied to the LCD panel 101 and the operator then observes lighttransmitted through the polarizer 130 to detect whether the LCD panel101 has a defect.

As described above, the apparatus for testing an appearance of the LCDpanel according to the present invention can be constructed such thatthe groove in which the jig is inserted is formed in the polarizerfixing unit which is rotatable whereby a polarizer having a large sizecan easily be positioned on the LCD panel and also a collision of thepolarizer with the camera or other component can effectively beprevented.

It will be apparent to those skilled in the art that variousmodifications and variation can be made in the present invention withoutdeparting from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. An apparatus for testing a liquid crystal display (LCD) panelcomprising: a test board to transmit light to an LCD panel that isplaced thereon; a polarizer fixing unit rotatably formed at the testboard and having a groove into which a polarizer is insertable; and astop formed at the test board to fix the polarizer fixing unit at apredetermined position.
 2. The apparatus of claim 1, wherein thepolarizer fixing unit is rotatable to position the groove substantiallyperpendicular to a ground.
 3. The apparatus of claim 1, furthercomprising a fixing member installed at one of the polarizer fixing unitand the stop to fix the polarizer fixing unit.
 4. The apparatus of claim3, wherein the fixing member includes a magnet.
 5. The apparatus ofclaim 1, further comprising a camera disposed at an upper portion of thetest board to capture the LCD panel to determine an aligned state of theLCD panel.
 6. The apparatus of claim 1, further comprising a jiginsertable into the polarizing fixing unit to support the polarizer. 7.The apparatus of claim 1, further comprising a rotational shaft torotate the polarizer fixing unit.
 8. An apparatus for testing a liquidcrystal display (LCD) panel comprising: a test board to transmit lightto an LCD panel that is placed thereon; a jig to support a polarizer;and a polarizer fixing unit formed at the test board and having a grooveinto which the jig is insertable to fix the polarizer.
 9. The apparatusof claim 8, wherein the polarizer fixing unit is rotatable.
 10. Theapparatus of claim 9, further comprising a rotational shaft to rotatethe polarizer fixing unit.
 11. The apparatus of claim 9, wherein thepolarizer fixing unit is rotatable to an angle at which the groove isperpendicular to a ground to thus insert the jig into the groove. 12.The apparatus of claim 8, further comprising: a stop for stopping therotation of the polarizer fixing unit; and a fixing member for fixingthe rotated polarizer fixing unit.
 13. A method of fabricating a liquidcrystal display (LCD) panel, the method comprising: preparing a firstand a second substrate; providing a switching device array on the firstsubstrate; providing a color filter substrate on the second substrate;bonding the first and second substrate together; forming a liquidcrystal layer between the substrates; cutting the attached substratesinto a plurality of unit LCD panels; performing a visual inspection of aunit LCD panel of the plurality of unit LCD panels using a visualinspection apparatus comprising: a test board to transmit light to aunit LCD panel disposed thereon; a polarizer fixing unit rotatablyformed at the test board and having a groove into which a polarizer isinsertable; and a stop formed at the test board to fix the polarizerfixing unit at a predetermined position.
 14. The method of claim 13,wherein the polarizer fixing unit is rotatable to position the groovesubstantially perpendicular to a ground.
 15. The method of claim 13,wherein the visual inspection apparatus further comprises a fixingmember installed at one of the polarizer fixing unit and the stop to fixthe polarizer fixing unit.
 16. The method of claim 15, wherein thefixing member includes a magnet.
 17. The method of claim 13, wherein thevisual inspection apparatus further comprises a camera disposed at anupper portion of the test board to capture the LCD panel to determine analigned state of the LCD panel.
 18. The method of claim 13, wherein thevisual inspection apparatus further comprises a jig insertable into thepolarizing fixing unit to support the polarizer.
 19. The method of claim13, wherein the visual inspection apparatus further comprises arotational shaft to rotate the polarizer fixing unit.
 20. The method ofclaim 13, wherein performing the visual inspection of a unit LCD panelincludes: disposing the unit LCD panel on the test board; andpositioning the polarizer on the unit LCD panel.
 21. The method of claim20, wherein positioning the polarizer on the unit LCD panel includes:inserting the polarizer into the groove of the polarizing fixing unit;and rotating the polarizing fixing unit to the predetermine position.22. The method of claim 20, wherein positioning the polarizer on theunit LCD panel includes aligning the unit LCD panel on the testboard.23. The method of claim 21, wherein aligning the unit LCD panel on thetestboard includes capturing an image of the unit LCD panel using thecamera.
 24. The method of claim 13, wherein performing the visualinspection of a unit LCD panel includes: transmitting light through theunit LCD panel from the testboard; detecting light transmitted throughthe unit LCD panel and the polarizer.